The present invention relates to a getter fixing device for a cathode ray tube (CRT), and more particularly to a getter fixing device which includes strips positioned outside a support member to attach a getter cover, resulting in fixing various forms of getter ring.
Generally in a CRT C as shown in FIG. 1, a shadow mask 1 is attached to the inner surface of a panel 2, a funnel 3 is joined to the rear of the panel 2, and a getter for improving the degree of vacuum of the CRT C is attached to the funnel 3.
With reference to FIGS. 2(a) and 2(b), the getter assembly 5 comprises a getter ring 6, a support member 7 for fixing the getter ring 6 by welding, and a getter cover 8 which is attached to the support member 7 and directs the diffusion of getter material 6a. The support member 7 and the getter cover 8 are conventionally made of heat resisting stainless steel, and the getter material 6a which is composed of Ba, A1 and Ni mixed in the usual ratio, is pressed in the inner surface of the getter ring 6. A R.F. coil 10 is used for heating the getter ring 6.
The getter material 6a, usually barium, in the getter ring 6 is released into the interior of the CRT C when the getter ring 6 of the getter assembly 5 is heated to about 1150.degree. C. by R. F. heating coil after the tube's atmosphere is evacuated during tube manufacture. The evaporated barium absorbs various residual gases in the CRT C by ionization phenomenon in aging process so that the internal degree of vacuum of the CRT C is maintained at about 10.sup.-7 Torr.
The getter cover 8 prevents the deposition of evaporated barium in the shadow mask 1 since the deposition of barium in the shadow mask 1 is not uniform.
The shadow mask 1 is subject to thermal expansion by heat over a temperature range of about 80.degree. C. generated by the collision of beam emitted from an electron gun 4. The getter assembly 5 must include the getter cover 8 to avoid deposition of getter material 6a in the shadow mask 1 since the deviation of a coefficient of thermal expansion according to the degree of the deposition (in case of such unequal deposition), results in a doming phenomenon which deteriorates screen characteristic and decreases brightness.
However, the conventional getter fixing device has a problem in that the plan for the getter cover 8, the support member 7 and the like must be changed according to the form of the getter ring 6. That is, FIGS, 2(a) and 2(b) illustrate the getter ring 6 in which a central attaching hole 6b is formed, and the getter cover 8 having a central sunk weld portion 8a formed by drawing, is affixed through the attaching hole 6b to the support member 7 by welding. However, it is well known in the art that, in addition to the shape illustrated in FIGS, 2(a) and 2(b), the getter ring 6 can be formed in various other shapes, for example, as a round plate shape as shown in cannot be directly affixed to the support member 7 because of the getter ring 6, resulting in plan changes of the constituent parts and, more particularly, limitation of standardization of the getter assembly 5 except the getter ring 6.